Highly smooth fiber, fabric, and formed article

ABSTRACT

The present invention relates to a highly smooth fiber comprising a fiber produced from a thermoplastic resin on which a mixed composition is deposited in an amount of 0.1 to 2.0 percent by weight of said fiber, said mixed composition comprising 50 to 85 percent by weight of a composition (A) consisting of an alkyl phosphate salt having an average number of carbon atoms of 6 to 14 and/or an alkyl phosphate salt having an average number of carbon atoms of 10 to 22 to which a polyoxyalkylene group is added; and 15 to 50 percent by weight of a composition (B) consisting of a polyoxyalkylene modified silicone containing amide group. 
     The present present invention also relates to a fabric or formed articles produced from such a highly smooth fiber.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a highly smooth fiber havinghydrophilic groups. More specifically, the present invention relates toa highly smooth fiber having an excellent processability in terms ofdispersion and fiber opening using air flow or a carding machine,produced by depositing a specific fiber treatment agent, therebyproviding anti-static properties, high smoothness, and hydrophilicproperties to a fiber consisting of a low-melting thermoplastic resin.The present invention also relates to a fabric or formed articlesproduced from such a highly smooth fiber.

2. Description of the Related Art

In various fields represented by the hygienic material field, there areused woven and non-woven fabrics produced from thermoplastic resins suchas polyolefins, polyesters and polyamides. These resins are uniformlydispersed using wet or dry processes, and subsequently adhered with hotair, compressed with hot rolls, and knitted or weaved usinghigh-pressure water flow or metal needles.

However, since fibers made of thermoplastic resins such as polyolefinsproduce much fiber--fiber and fiber-metal friction in the dry cardingprocess, static electricity is generated and twining occurs.

Because of the present discreteness and improved quality and performanceof products, functional thermoplastic resins are often used. In some ofthese applications, there are used fibers which produce morefiber--fiber and fiber-metal friction than do conventional fibers. Suchfibers include resins suitable for low-temperature processing and thosehaving high tackiness. Also, for improving processing efficiencies,increase in processing speed is attempted.

For these reasons, various fiber finishing agents have been proposed forimparting anti-static properties or smoothness to the fibers. Widelyused fiber finishing agents include waxes, fatty acid-based fats andoils, and quaternary ammonium salts containing long-chain alkyl groups.However, none of these agents impart sufficient smoothness to thefibers.

On the other hand, silicone-based finishing agents are well known toimpart high smoothness to the fibers. For example, emulsion-polymerizeddimethyl siloxane and amine-modified silicone have been proposed(Japanese Patent Application Publication NO 48-1480). However, bothemulsion-polymerized dimethyl siloxane and amine-modified silicone havepoor anti-static properties, interfere with the hydrophilic propertiesof the fiber, and cause the non-woven fabrics to turn yellow.

For imparting hydrophilic properties to fibers, treatment withpolyether-modified silicone has been proposed (e.g., Japanese PatentApplication Laid-open Nos. 63-303184, 1-148879 and 2-169774). However,polyether-modified silicone imparts hydrophilic properties but does notimpart smoothness to fibers. Therefore, highly smooth fibers providedwith higher smoothness, anti-static properties, and hydrophilicproperties have still been demanded.

SUMMARY OF THE INVENTION

It is the object of the present invention to improve the processabilityof thermoplastic fibers having a melting point of 120° C. or below, aswell as to improve the adhesiveness and tackiness which has been theproblem in the above-described prior art. It is another object of thepresent invention to improve by air flow the evenness of webs producedby fiber opening of fibers comprising thermoplastic resins such aspolyolefins.

In other words, the object of the present invention is to provide highlysmooth fibers having hydrophilic properties, anti-static properties, andexcellent smoothness, as well as fabrics and formed fibrous articlesproduced by such fibers.

The inventors of the present invention conducted repeated studies forsolving the above problems, and found that the above problems weresolved by depositing a mixture of special surfactants on the surface offibers as the finishing agents, and completed the present invention.

According to a first aspect of the present invention, there is provideda highly smooth fiber produced from a thermoplastic resin on which amixed composition is deposited in an amount of 0.1 to 2.0 percent byweight of said fiber, said mixed composition comprising 50 to 85 percentby weight of a composition (A) consisting of an alkyl phosphate salthaving an average number of carbon atoms of 6 to 14 and/or an alkylphosphate salt having an average number of carbon atoms of 10 to 22 towhich a polyoxyalkylene group is added; and 15 to 50 percent by weightof a composition (B) consisting of a polyoxyalkylene modified siliconecontaining amide group.

According to a second aspect of the present invention, there is provideda highly smooth fiber according to the first aspect, wherein said fiberproduced from a thermoplastic resin is a staple having a fiber length of30 mm or less.

According to a third aspect of the present invention, there is provideda highly smooth fiber according to the first or second aspect, whereinat least one component of the thermoplastic resin constituting saidstaple has a melting point of 120° C. or below.

According to a fourth aspect of the present invention, there is provideda highly smooth fiber according to any of the first through thirdaspects, wherein at least one component of the thermoplastic resinconstituting said staple is a polyolefin-based resin.

According to a fifth aspect of the present invention, there is provideda highly smooth fiber according to any of the first through thirdaspects, wherein at least one component of the thermoplastic resinconstituting said staple is a polyester-based resin.

According to a sixth aspect of the present invention, there is provideda highly smooth fiber according to any of the first through thirdaspects, wherein at least one component of the thermoplastic resinconstituting said staple is a polyamide-based resin.

According to a seventh aspect of the present invention, there isprovided a highly smooth fiber according to any of the first throughsixth aspects, wherein the thermoplastic resin constituting said stapleis an ethylene-acrylic ester-maleic anhydride terpolymer.

According to an eighth aspect of the present invention, there isprovided a highly smooth fiber according to any of the first throughseventh aspects, wherein said fiber produced from thermoplastic resinsis a composite fiber comprising the first component containing at least20 percent by weight of an ethylene-acrylic ester-maleic anhydrideterpolymer, and forming at least a portion of the surface of said fiberin the lengthwise direction; and the second component consisting of athermoplastic resin having a melting point at least 20° C. higher thanthe melting point of the first component.

According to a ninth aspect of the present invention, there is provideda non-woven fabric produced using a highly smooth fiber according to anyof the first through eighth aspects.

According to a tenth aspect of the present invention, there is provideda knitted or woven fabric produced using a highly smooth fiber accordingto any of the first through eighth aspects.

According to an eleventh aspect of the present invention, there isprovided a fibrous formed article produced using a highly smooth fiberaccording to any of the first through eighth aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a front view of simplified air-laid equipment.

FIG. 2 depicts a top view of the main part of the simplified air-laidequipment.

Each of the numbers indicated in FIGS. 1 and 2 means parts of theequipment as shown below.

1: First fiber opening blade

2: Second fiber opening blade

3: fiber collecting conveyor

4: Suction

5: Sprocket to rotate fiber opening blades

6: Rotating motor

7: Sample feeding blower

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will next be described in detail.

Thermoplastic fibers used in the present invention are produced fromthermoplastic resins; for example, polyolefin-based, polyester-based,and polyamide-based resins.

Polyolefin-based resins include homopolymer of ethylene or propylene,copolymers of those with other α-olefins, and mixtures thereof.Copolymers with α-olefins include copolymers or terpolymers of olefins,mainly propylene. Specific examples of these copolymers are thecopolymers of propylene with ethylene, butene-1 or 4-methylpentene-1.

Ethylene-based copolymers or terpolymers include vinyl ester copolymerssuch as vinyl acetate; copolymers of unsaturated carboxylic ester suchas methyl acrylate, ethyl acrylate, isobutyl acrylate and methylmethacrylate; copolymers of unsaturated carboxylic acid such as acrylicacid, methacrylic acid and maleic anhydride; ethylene-vinyl alcoholcopolymer; and vinyl compounds such as vinyl chloride and styrene.

Polyester-based resins include, for example, polyethylene terephthalate,polybutylene terephthalate, poly (ethylene terephthalate-co-ethyleneisophthalate), and copolymerized polyether esters.

Depending on applications, mixtures of polyolefin resins withpolyester-based resins, polyamide-based resins or elastomers such asethylene-propylene rubber may be selected.

These thermoplastic fibers may be combined with additives for impartingthe functionality to the fibers within the range for achieving theobject of the present invention, and the type and amount of theseadditives may be selected as required.

Next, the mixture of surfactant compositions (A) and (B) used in thepresent invention (hereafter called "the finishing agent") will bedescribed.

The composition (A) comprises one or more compounds selected from agroup consisting of alkyl phosphate salts having an average number ofcarbon atoms of 6 to 14, and/or alkyl phosphate salts having an averagenumber of carbon atoms of 10 to 22 to which a polyoxyalkylene group isadded. The alkyl phosphate salt is preferably a fully-neutralizedmonophosphate or diphosphate salt of saturated or unsaturated alkylgroup having a number of carbon atoms of 6 to 14, preferably 8 to 12,such as octyl alcohol, decyl alcohol, or dodecyl alcohol. These alkylgroups may have side chains. Although the neutralizing salts may includealkali metals such as K and Na, as well as ammonia and amines, alkalimetals are preferred from the point of view of anti-static properties.

These alkyl phosphate salts are used for imparting hydrophilic andanti-static properties to fibers. However, if the average number ofcarbon atoms in the alkyl group is more than 14, the hydrophilicproperties become degraded, and if it is less than 6, smoothnessdecreases.

As the composition (A), a polyoxyalkylene group may be added to thealkyl phosphate salt. The polyoxyalkylene group may be an alkylene oxidesuch as ethylene oxide, propylene oxide, or butylene oxide; preferablyethylene oxide alone or a random or block copolymer of ethylene oxideand propylene oxide. The number of moles added is 2 to 10 moles,preferably 3 to 7 moles. When a polyoxyalkylene is added, the averagenumber of carbon atoms of the alkyl group is 10 to 22. If the number ofcarbon atoms is less than 10, smoothness decreases, and if it is morethan 22, anti-static properties become degraded.

The amount of the composition (A) added to the finishing agent is 50 to85 percent by weight, preferably 60 to 80 percent by weight. If theamount is less than 50 percent by weight, anti-static properties areinsufficient, and if it exceeds 85 percent by weight, smoothnessdecreases, and card twining increases.

The typical polyoxyethylene modified silicone containing amide groupused as the composition (B) is represented by the following structuralformula: ##STR1## where each of R and R₁ is independently a two-valenthydrocarbon group having a number of carbon atoms of 1 to 10, R₂ is amonovalent hydrocarbon group having a number of carbon atoms of 10 to20, n is 1 to 15, each of x and y is independently a number of 1 ormore, and x+y is 10 to 2,000.

If x+y in the above formula is less than 10, the composition (B) doesnot impart smoothness to the fiber, and is x+y exceeds 2,000, thecomposition (B) is difficult to emulsify, and a stable finishing agentcannot be obtained.

R₂ is a monovalent hydrocarbon group having 10 to 20 carbon atoms, andthe examples include straight-chain or branched alkyl groups such asundecyl, lauryl, myristyl, and cetyl groups; alkenyl groups such asoleyl groups; alkaryl groups such as octylphenyl and nonylphenyl groups;and aralkyl groups such as phenyloctyl groups.

In the above formula, n is an integer of 1 or more, preferably 3 to 15.If it is less than 1, hydrophilic and anti-static properties lower, andif it is more than 15, smoothness decreases.

The divalent hydrocarbon groups of R and R₁ include alkylene groups suchas methylene, ethylene and trimethylene groups; and alkylene aryl groupssuch as --C₂ H₄ --C₆ H₄ --; preferably alkylene groups, and morepreferably methylene group.

The amount of the composition (B) in the finishing agent is 15 to 50percent by weight, preferably 20 to 40 percent by weight. If the amountis less than 15 percent by weight, smoothness decreases, and if itexceeds 50 percent by weight, anti-static properties become poor.

Compositions other than compositions (A) and (B) required for thethermoplastic resin constituting the fibers, fabrics, or formed articlesmay be added to the finishing agent within the range to achieve theobject of the present invention.

The amount of the finishing agent deposited on the above thermoplasticfibers is 0.1 to 2.0 percent by weight, preferably 0.3 to 1.5 percent byweight.

If the amount is less than 0.1 percent by weight, anti-staticproperties, hydrophilic properties, and smoothness of the fibers becomepoor, and if it exceeds 2.0 percent by weight, problems will arise suchas twining to the cylinder in the carding process and tackiness of thefabrics.

The methods for depositing these finishing agents on thermoplasticfibers are not limited to a specific method, but may be any methodsknown to the art, such as deposition by contacting with an oiling roll,immersing in a dip tank, and spraying during spinning or drawingprocesses, as well as deposition, after processing, onto laminatedfibers such as webs, fabrics such as non-woven fabric, or formedarticles, by contacting, immersing, or spraying.

The highly smooth fibers of the present invention are the abovethermoplastic fibers on which a finishing agent is deposited, and theirprofile structure may be either a single or composite structure. Thecross-sectional form of the fiber may be circular or deformed or hollow.

The form of the fiber may be altered depending on the method forprocessing into fabrics or formed articles. In the fiber laminatingmethod using air flow opening such as the air-laid method, staples of alength of 30 mm or less produce evenly opened fiber laminates, whethercrimped or not. In particular, although fibers containing athermoplastic resin of a low melting point of 120° C. or below or anadhesive or tacky thermoplastic resin cannot be opened evenly as theyare, due to the large fiber friction produced, the highly smooth fiberson which the finishing agent of the present invention is depositedproduce highly even webs due to reduced friction between fibers. Also inspinning processes such as fine spinning, spun yarns having a lowmelting point or adhesiveness, which were difficult to produce inconventional methods, may be produced because of small amounts offiber-metal friction.

Regarding the function of the finishing agent, the behavior of asheath-and-core type composite fiber in dry opening will next bedescribed.

Sheath-and-core type composite fibers having adhesiveness with othermaterials, which is a high functionality, have been used. In order toimpart adhesiveness with other materials to these fibers, aethylene-ethyl acrylate-maleic anhydride terpolymer (melting point=80°C., melt flow rate=20 g/10 min at 190° C.) is used for the sheathcomponent. Since these fibers produce much fiber--fiber and fiber-metalfriction in the carding process, ordinary finishing agent prevents thegeneration of static electricity, but cannot open fibers sufficientlydue to much fiber--fiber friction being produced, resulting in unevenwebs. By the use of the finishing agent of the present invention,however, fiber--fiber friction is reduced because of excellentanti-static properties and smoothness, and highly even webs areproduced.

As another example, a sheath-and-core type composite fiber consisting ofhydrophobic thermoplastic resins such as low-densitypolyethylene/polypropylene cannot produce evenly laminated fibers in thefiber laminating process using air-flow opening, because the fiberitself is strongly hydrophobic, and static electricity is generated infibers due to friction between fibers and between equipment and fibers.Therefore, the speed of the equipment must be lowered, and the equipmentmust be cleaned very often, both causing productivity to lower.

On the other hand, the sheath-and-core type composite fiber on which thefinishing agent of the present invention has been applied excels insmoothness and anti-static properties and can be opened evenly, andlittle static electricity is generated between fibers or betweenequipment and fibers.

Also, among smooth fibers of the present invention, side-by-side type,sheath-and-core type, radially split type and sea-and-island typecomposite fibers maintain the shape of absorbing materials by mixing andheat-treating the cut staples with water-absorbing materials such aspulp or high polymers absorbent. Although ordinary thermoplasticcomposite fibers are difficult to mix uniformly with pulp and the likebecause of static electricity generated due to friction between fibers,the smooth fibers of the present invention slightly lowerwater-absorbing properties, produce slight unevenness of the absorbingmaterials, and excel in water dispersion, because of their excellenthydrophilic properties and smoothness.

Smooth fibers, fabrics, and formed articles of the present invention canbe used for producing adhesive sheets, elastic non-woven fabrics, shockabsorbers, yarn to prevent spining yarn from getting untied, shapemaintenance of absorbing materials, water-diffusing membranes, absorbingpads, structural reinforcing fibers in civil engineering andconstruction fields, and fiber-blended mats with other fibers.

EXAMPLES

The present invention will be described in further detail by way ofreferring to examples, but the present invention is not limited to thefollowing Examples and Comparative Examples, as far as the scope of thepresent invention is not exceeded.

In these Examples, the following methods were used for evaluatingproperties.

(1) Anti-static property: A web was produced from 40 g of sample fibersof a length of 51 mm using a test carding machine at a temperature of20° C., a relative humidity of 45%, and a speed of 7 m/min; and thevoltage of static electricity generated in the web was measured. Theresults were evaluated according to the following criteria. When thevoltage was lower than 100 V, the web was evaluated to be suitable forpractical use.

∘: Less than 100 V

Δ: 100 V or more, and less than 500V

X: 500 V or more

(2) Card twining: A web was produced from 40 g of sample fibers of alength of 51 mm using a miniature test carding machine at a temperatureof 30° C., a relative humidity of 80%, and a speed of 7 m/min. Themachine was subsequently stopped, and the cylinder was visuallyobserved. The results were evaluated according to the followingcriteria.

∘: No twining

Δ: Partial twining

X: Almost complete twining

(3) State of web 1: The state of the web produced in the above methodwas observed, and the results were evaluated according to the followingcriteria.

∘: Web is even, without neps.

Δ: Some neps are produced.

X: Web is uneven.

(4) Hydrophilic property of fiber: A cylindrical basket having adiameter of 3 cm, a height of 8 cm, a weight of 3 g and made of copperwire net was filled with 5 g of the sample having a fiber length of 51mm and finely carded using a miniature carding machine, and was allowedto float on the surface of water in a water vessel at 25° C. The timewas measured until the sample, together with the basket, sank in water.

When the time was 10 seconds or less, the hydrophilic property wasevaluated as good; when the time was 30 seconds or more, the hydrophilicproperty was evaluated as poor and represented by X.

(5) Hydrophilic property of non-woven fabric: A web produced using aminiature carding machine was heat-treated using a suction drier(processing time=20 seconds, wind velocity=2 m/sec, heatingtemperature=133°) to form a non-woven fabric. On the surface of theresultant non-woven fabric having a METSUKE (weight per unit area) of 25g/m², 10 drops of water were dropped from a height of 1 cm using apipette at a temperature of 20° C. and a relative humidity of 45%, andthe number of droplets which disappeared within 30 seconds was counted.

(6) State of web 2: Webs were produced from sample fibers of lengths of3, 5, 10, 30 and 45 mm using air-laid equipment shown in FIGS. 1 and 2,and evaluated for their ability to be opened.

The fibers fed from the sample feeding blower 7 were opened by the firstopening blade 1 and the second opening blade 2 rotated by the openingblade rotating sprocket 5 connected to the rotating motor 6, and fellonto the fiber collecting conveyor 3 moving in the direction indicatedby the arrow in FIGS. 1 and 2. A web was produced in such a way, thestate of the web was visually observed, and evaluated according to thefollowing criteria.

∘: Well opened, even web

Δ: Partially un-opened

X: Insufficiently opened, uneven web

EXAMPLE Examples 1-11, Comparative Examples 1-11

Fibers having a fineness of 2 deniers were produced to have profiles ofa single structure (single type), a sheath-and-core structure, aside-by-side structure, a structure radially divided into 16 portions(split type), and a sea-and-island structure (sea-and-island type) wereproduced from a thermoplastic resin consisting of the followingcomponents using a conventional melt spinning method, and physicalproperties were evaluated after depositing the finishing agent indicatedin Table 1 and 2 on the fibers.

Component A: Polypropylene

230° C. melt flow rate (hereafter abbreviated as MFR)=18 g/10 min

Component B: Polyester

Inherent viscosity measured in o-chlorophenol at 35° C.,

IV=0.65

Component C: Low-density polyethylene

MFR at 190° C.=20 g/10 min

Component D: Ethylene-methyl acrylate-maleic anhydride terpolymer

MFR at 190° C.=14 g/10 min

Component E: a blend of ethylene-propylene rubber (MFR at 190° C.=4.5g/10 min) and low-density polyethylene (MFR at 190° C.=20 g/10 min)=3/7by weight

Component F: High-density polyethylene

MFR at 190° C.=15 g/10 min

Examples 12-17, Comparative Examples 12-16

Fibers of a fineness of 2 deniers were produced using thermoplasticresins of compositions A to F in the same way as in Examples 1 to 11.Finishing agents of various compositions shown in Table 3 were depositedon these fibers, the fibers were cut, and webs were produced usingair-laid equipment.

                                      TABLE 1    __________________________________________________________________________                Exam-                    Exam-                        Exam-                            Exam-                                Exam-                                    Exam-                                        Exam-                                            Exam-                                                Exam-                                                    Exam-                                                        Exam-                ple 1                    ple 2                        ple 3                            ple 4                                ple 5                                    ple 6                                        ple 7                                            ple 8                                                ple 9                                                    ple 10                                                        ple    __________________________________________________________________________                                                        11    Octyl phosphate K-salt                70  20  50              85  50      70  70    Lauryl phosphate K-salt                    50      30      50          35    POE(5) Lauryl       20      50          35  50    phosphate K-salt    POE(5) Myristyl         20    phosphate K-salt    B    Amide polyoxyethylene                30  30  30  50  50  50  15  15  15  30  30    modified silicone*1    Dimethyl silicone emulsion    (Mw = 1 million)    Amine modified silicone*2    Polyether modified    silicone (EO modified)*3    Stearyl phosphate K-salt    (C24) Alkyl phosphate    K-salt POE(5)    Amount of deposition (%)                0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.3 1.5    Resin    Fiber structure                Sheath-                    Sheath-                        Sheath-                            Sheath-                                Sea-                                    Single                                        Sheath-                                            Split                                                Split                                                    Sheath-                                                        Sheath-                core                    core                        core                            core                                island  core        core                                                        core    First component                A   B   A   B   A   E   A   A   A   A   A    (core, island etc.)    Second component                D   D   D   C   D       E   C   C   D   D    (sheath, sea, etc.)    Card twining    Anti-static properties                ◯                    ◯                        ◯                            ◯                                ◯                                    ◯                                        ◯                                            ◯                                                ◯                                                    ◯                                                        ◯    Card twining                ◯                    ◯                        ◯                            ◯                                ◯                                    ◯                                        ◯                                            ◯                                                ◯                                                    ◯                                                        ◯    State of web 1                ◯                    ◯                        ◯                            ◯                                ◯                                    ◯                                        ◯                                            ◯                                                ◯                                                    ◯                                                        ◯    Hydrophilic properties                3.1 3.4 3.5 4.5 4.3 4.0 3.0 3.5 3.5 4.0 3.1    Non-woven fabric    Hydrophilic properties                10  10  10  10  10  10  10  10  10  10  10    __________________________________________________________________________

                                      TABLE 2    __________________________________________________________________________                Com-                    Com-                        Com-                            Com-                                Com-                                    Com-                                        Com-                                            Com-                                                Com-                                                    Com-                                                        Com-                parative                    parative                        parative                            parative                                parative                                    parative                                        parative                                            parative                                                parative                                                    parative                                                        parative                Exam-                    Exam-                        Exam-                            Exam-                                Exam-                                    Exam-                                        Exam-                                            Exam-                                                Exam-                                                    Exam-                                                        Exam-                ple 1                    ple 2                        ple 3                            ple 4                                ple 5                                    ple 6                                        ple 7                                            ple 8                                                ple 9                                                    ple 10                                                        ple    __________________________________________________________________________                                                        11    Octyl phosphate K-salt                70  70  70          70  70  100     40  90    Lauryl phosphate K-salt    POE(5) Lauryl    phosphate K-salt    POE(5) Myristyl    phosphate K-salt    B    Amide polyoxyethylene   30  30  30  30      100 60  10    modified silicone*1    Dimethyl silicone emulsion                30    (Mw = 1 million)    Amine modified silicone*2                    30    Polyether modified  30    silicone (EO modified)*3    Stearyl phosphate K-salt                            70    (C24) Alkyl phosphate       70    K-salt POE(5)    Amount of deposition (%)                0.5 0.5 0.5 0.5 0.5 0.07                                        2.5 0.5 0.5 0.5 0.5    Resin    Fiber structure                Sheath-                    Sheath-                        Sheath-                            Sheath-                                Sheath-                                    Sheath-                                        Sheath-                                            Sheath-                                                Sheath-                                                    Sheath-                                                        Sheath-                core                    core                        core                            core                                core                                    core                                        core                                            core                                                core                                                    core                                                        core    First component                A   A   A   A   A   A   A   A   A   A   A    (core, island, etc.)    Second component                D   D   D   D   D   D   D   D   D   D   D    (sheath, sea etc.)    Card twining    Anti-static properties                Δ                    Δ                        ◯                            Δ                                Δ                                    X   ◯                                            ◯                                                Δ                                                    Δ                                                        ◯    Card twining                ◯                    ◯                        Δ                            Δ                                Δ                                    X   X   Δ                                                X   ◯                                                        Δ    State of web                ◯                    ◯                        ◯                            ◯                                Δ                                    X   X   Δ                                                X   Δ                                                        Δ    Hydrophilic properties                X   X   3.1 X   12.2                                    X   3.0 3.0 28.4                                                    4.5 1.1    Non-woven fabric    Hydrophilic properties                 0   0  10   0   4   0  10  10   4  10  10    __________________________________________________________________________

                                      TABLE 3    __________________________________________________________________________                                        Com-                                            Com-                                                Com-                                                    Com-                                                        Com-                                        parative                                            parative                                                parative                                                    parative                                                        parative                Exam-                    Exam-                        Exam-                            Exam-                                Exam-                                    Exam-                                        Exam-                                            Exam-                                                Exam-                                                    Exam-                                                        Exam-                ple 12                    ple 13                        ple 14                            ple 15                                ple 16                                    ple 17                                        ple 12                                            ple 13                                                ple 14                                                    ple 15                                                        ple    __________________________________________________________________________                                                        16    Octyl phosphate K-salt                70  70  70  30  30  50  70  70  70  70  70    POE(5) Lauryl           40  20    phosphate K-salt    Amide polyoxyethylene                30  30  30  30  50  50              30  30    modified silicone*1    Dimethyl silicone emulsion          30    (Mw = 1 million)    Amine modified silicone*2               30    Polyether modified                          30    silicone (EO modified)*3    Amount of deposition (%)                0.5 1.0 0.2 0.5 0.5 0.5 0.5 0.5 0.5 0.5 2.5    Fiber    Fiber structure                Sheath-                    Single                        Sheath-                            Sheath-                                Sheath-                                    Split                                        Sheath-                                            Sheath-                                                Sheath-                                                    Sheath-                                                        Single                core    core                            core                                core    core                                            core                                                core                                                    core    First component                A   E   B   A   A   A   A   A   A   A   E    (core, island etc.)    Second component                D       C   E   D   F   D   D   D   D    (sheath, sea etc.)    Fiber length (mm)                10  10   5  10   3  30  10  10  10  45  10    Air-laid    State of web 2                ◯                    ◯                        ◯                            ◯                                ◯                                    ◯                                        X   Δ                                                Δ                                                    X   X    __________________________________________________________________________

The details of compounds shown in Tables 1 to 3 are as follows:

*1 Polyoxyethylene modified silicone containing amide group ##STR2##

*2 Amine modified silicone ##STR3##

*3 Polyether modified silicone ##STR4##

Since smooth fibers consisting of the thermoplastic fibers of thepresent invention excel in hydrophilic and anti-static properties aswell as in smoothness, the processability of thermoplastic fibers havinglow melting points or thermoplastic fibers having adhesiveness ortackiness and having large fiber--fiber and fiber-metal friction isimproved. Therefore, the webs produced by smooth fibers of the presentinvention produce no neps, and fabrics or formed articles of the presentinvention maintain good evenness.

Even webs may be produced also from ordinary thermoplastic fibers suchas polyolefins by fiber opening using air flow.

We claim:
 1. A highly smooth fiber comprising a fiber produced from athermoplastic resin on which a mixed composition is deposited in anamount of 0.1 to 2.0 percent by weight of said fiber, said mixedcomposition comprising 50 to 85 percent by weight of a composition (A)consisting of an alkyl phosphate salt having an average number of carbonatoms of 6 to 14 and/or an alkyl phosphate salt having an average numberof carbon atoms of 10 to 22 to which a polyoxyalkylene group is added;and 15 to 50 percent by weight of a composition (B) consisting of apolyoxyalkylene modified silicone containing an amide-group.
 2. Thehighly smooth fiber according to claim 1, wherein said fiber producedfrom a thermoplastic resin is a staple having a fiber length of 30 mm orless.
 3. The highly smooth fiber according to claim 2, wherein at leastone component of the thermoplastic resin constituting said staple has amelting point of 120° C. or below.
 4. The highly smooth fiber accordingto claim 2, wherein at least one component of the thermoplastic resinconstituting said staple is a polyolefin-based resin.
 5. The highlysmooth fiber according to claim 2, wherein at least one component of thethermoplastic resin constituting said staple is a polyester-based resin.6. The highly smooth fiber according to claim 2, wherein at least onecomponent of the thermoplastic resin constituting said staple is apolyamide-based resin.
 7. The highly smooth fiber according to claim 2,wherein the thermoplastic resin constituting said staple is anethylene-acrylic ester-maleic anhydride terpolymer.
 8. The highly smoothfiber according to claim 1, wherein said fiber produced fromthermoplastic resins is a composite fiber comprising the first componentcontaining at least 20 percent by weight of an ethylene-acrylicester-maleic anhydride terpolymer, and forming at least a portion of thesurface of said fiber in the lengthwise direction; and the secondcomponent consisting of a thermoplastic resin having a melting point atleast 20° C. higher than the melting point of the first component.
 9. Anon-woven fabric comprising a highly smooth fiber according to claim 1.10. A knitted or woven fabric produced by using a highly smooth fiberaccording to claim
 1. 11. A fibrous formed article comprising a highlysmooth fiber according to claim 1.